This invention relates to a process for developing or peeling an alkali-type photosensitive film and an apparatus used therein. More particularly, this invention relates to a process for regenerating a developing or peeling solution for alkali-type photosensitive film comprising depositing a suspension of photosensitive film released and contained in the developing or peeling solution in floc state and removing the flocculated floating deposit from the developing or peeling solution for reuse and an apparatus used therein.
Heretofore, development or peeling of alkali-type photosensitive film has been conducted batch-wise or continuously by dipping and alkali-type photosensitive film in a several percent alkaline solution or spraying a several percent alkaline solution over the alkali-type photosensitive film. During the development, unexposed portions of the alkali-type photosensitive film become a suspension in suspended state in the developing solution. During the peeling, the exposed portions become a suspension in a suspended state in the peeling solution or sometimes there are present film flakes in the peeling solution.
Defects of prior art processes are that it is difficult to remove completely the suspension in a suspended state by filtration even if the film flakes may be removed by filtration, and much man-power is necessary for renewal of filtering area, so that the developing or peeling solution is changed after used for treating the photosensitive film of 0.5 to 0.7 m.sup.2 /liter and the waste developing or peeling solution is neutralized in an alkali waste treating apparatus or is filled in drum cans for disposal. Considering water pollution, much disposal cost is necessary.
On the other hand, the production of printed wiring boards is changing from the printing method to the so-called photosensitive film method. As to the photosensitive film method, a so-called alkali-type process wherein the photosensitive film is developed or peeled imagewisely by using an alkaline aqueous solution is increasing compared with a process wherein the photosensitive film is developed or peeled imagewisely using a solvent. Thus, the treatment of increased alkali waste with low cost is necessary and a demand for development or imagewise peeling of alkali-type photosensitive film while recycling the developing or peeling solution becomes stronger.